This invention relates generally to an improvement for an internal combustion engine, and specifically in the intake and exhaust valve system to enhance the charge volume per unit time for intake and exhaust, and provide other improvements for greatly increasing the efficiency of the engine, the total combustion process and the reduction of pollution.
Attempts have been made in the past to employ what are termed "concentric intake and exhaust valve mechanisms" in internal combustion engines. One example is shown in U.S. Pat. No. 1,350,800 issued to Greuter, Aug. 24, 1920, which shows a single concentric intake and exhaust valve system per cylinder employed to afford greater area for inlet and exhaust ports. In order to attempt to achieve an operational model, Greuter discloses a very complex camming system to insure that the intake and exhaust valves are seated properly. Specifically, cam surfaces are used to close the valve as well as open the valve. The great deficiency of Greuter (apart from the extremely complex and expensive camming system which he finds necessary in order to make his system attempt to work) is the massive weight of the single concentric valve assembly. The excessive surface area of the single concentric valve assembly in the combustion chamber creates extreme loading problems resulting from exhaust compression after the combustion stroke because the exhaust valve must open against high gas pressures in the cylinder. The extremely large surface area presented by the single exhaust valve (in conjunction with the surface area of the intake valve) puts great demand on the system, making it impractical of operation. In another system showing a single concentric valve, U.S. Pat. No. 1,950,911 issued to Zahodiakin in Mar. 13, 1934, the patentee discloses a sleeve-like concentric intake and exhaust valve system to reduce the exhaust gas pressure on the exhaust valve. Again the system is quite impractical due to the size and mass of the valves presented. The deficiencies shown in the prior art amplify and clearly demonstrate problems which have not allowed a concentric valve system to be practical in a conventional combustion engine.
The present invention overcomes the problems of the prior art by providing a multiple, concentric intake and exhaust valve system for an internal combustion engine. These improvements are, greatly increased volume of charge per unit time, when coupled with a cam shaft profile of longer duration of full valve opening over the average range of piston travel, through the engine per intake stroke, while at the same time reducing the mass of each concentric valve assembly allowing for conventional type cam and lifter action. This greatly reduces the exhaust pressure on each concentric valve assembly, and enhances the swirl characteristics of the charge by providing the capability of sequential intake of the charge per cylinder by sequentially opening and closing the intake valves in each cylinder.
In the preferred embodiment, four sets of concentric valve assemblies are used per cylinder, which allows for four intake valves and four exhaust valves per cylinder which are disposed to obtain an optimum circumferential valve area for flow into and out of the cylinder.
Improved efficiency is attributed to the increased volume of charge flow per unit time into the cylinder while improving intake charge velocity. The second effect is that by swirling the charge, a more thorough, homogeneous mixture is achieved in the combustion chamber after the intake stroke. This allows a more complete combustion of the charge, deriving more energy per stroke of combustion.
Another benefit of the multiple valve intake and exhaust valve system is that one side of the cylinder can be in fluid communication with one fuel source, and at the same time the other side of the cylinder can be in fluid communication with another fuel source. This allows the mixing of two separate fuels such as gasoline and alcohol in the cylinder. Another important result of the invention is the fact that the increased charge circumferential area available for the intake charge entry and exhaust expulsion (which greatly enhances the volume of flow per unit time through the engine) also reduces the mechanical acceleration demands for lifting the intake and exhaust valves. With the greater circumferential distance achieved, the valves need be opened less to achieve optimum charge volume per unit time. Duration of optimum valve open position is no longer a limiting factor of camshaft acceleration.
The primary problem in conventional, four cycle, internal combustion engines is the inability in the time available per intake stroke to get sufficient charge volume into the cylinder, resulting in low volumetric efficiency in conventional operating RPM ranges. The intake charge volume per unit time is conventionally limited by demands of cam ramp acceleration resulting in time limitations on the duration of full valve opening. The present invention allows for optimum open valve duration.